Spatial-temporal pattern of, and driving forces for, urban heat island in China

Urban heat islands (UHIs) have very large negative effects on local climate features and ecological environments. However, the larger-scale temporal and spatial patterns of UHIs are still unclear. Our research explored the large-scale spatial and temporal patterns of UHIs in 155 cities across China by collecting observational data from 310 meteorological stations over a 30-year period (1984-2013). The results suggested that the UHI intensity has linearly increased over the past 30 years and is strongest in summer across different years. The UHI intensity in inland cities is significantly higher than that in coastal cities; cities in arid areas had higher UHI intensities than those in humid areas; cities in middle or high mountain areas had higher UHI intensities compared to those located in the other landforms in China. There are no significant differences in UHI intensity between cities located in different climatic zones or between cities with different GDP levels, population sizes and industrial structures. Additionally, the relationships between the UHI intensity and several factors, such as meteorological conditions, GDP level and population size, were analyzed. Our results showed that average wind speed, average precipitation and relative humidity had a significant negative correlations with UHI intensity, whereas there was no significant correlation between anthropogenic factors and UHI intensity. Our research indicated that we should consider the local climate and landscape to eliminate UHI hazards in the future urbanization processes.